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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 1 Jun 2021 12:16:14 -0700
Message-ID: <CAKwvOdnUdQHMungT97KcECo-HzMSLeDM7s=JCGh5XwOkR84+Rg@mail.gmail.com>
Subject: Re: [PATCH 1/3] hexagon: Handle {,SOFT}IRQENTRY_TEXT in linker script
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Brian Cain <bcain@codeaurora.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "open list:QUALCOMM HEXAGON..." <linux-hexagon@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Thu, May 20, 2021 at 6:13 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Patch "mm/slub: use stackdepot to save stack trace in objects" in -mm
> selects CONFIG_STACKDEPOT when CONFIG_STACKTRACE_SUPPORT is selected and
> CONFIG_STACKDEPOT requires IRQENTRY_TEXT and SOFTIRQENTRY_TEXT to be
> handled after commit 505a0ef15f96 ("kasan: stackdepot: move
> filter_irq_stacks() to stackdepot.c") due to the use of the
> __{,soft}irqentry_text_{start,end} section symbols. If those sections
> are not handled, the build is broken.
>
> $ make ARCH=hexagon CROSS_COMPILE=hexagon-linux- LLVM=1 LLVM_IAS=1 defconfig all
> ...
> ld.lld: error: undefined symbol: __irqentry_text_start
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
>
> ld.lld: error: undefined symbol: __irqentry_text_end
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
>
> ld.lld: error: undefined symbol: __softirqentry_text_start
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
>
> ld.lld: error: undefined symbol: __softirqentry_text_end
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
> >>> referenced by stackdepot.c
> >>>               stackdepot.o:(filter_irq_stacks) in archive lib/built-in.a
> ...
>
> Add these sections to the Hexagon linker script so the build continues
> to work. ld.lld's orphan section warning would have caught this prior to
> the -mm commit mentioned above:
>
> ld.lld: warning: kernel/built-in.a(softirq.o):(.softirqentry.text) is being placed in '.softirqentry.text'
> ld.lld: warning: kernel/built-in.a(softirq.o):(.softirqentry.text) is being placed in '.softirqentry.text'
> ld.lld: warning: kernel/built-in.a(softirq.o):(.softirqentry.text) is being placed in '.softirqentry.text'
>
> Fixes: 505a0ef15f96 ("kasan: stackdepot: move filter_irq_stacks() to stackdepot.c")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1381
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks for the series, and sorry I didn't get around to reviewing
before I took time off last week.

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  arch/hexagon/kernel/vmlinux.lds.S | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/hexagon/kernel/vmlinux.lds.S b/arch/hexagon/kernel/vmlinux.lds.S
> index 35b18e55eae8..20f19539c5fc 100644
> --- a/arch/hexagon/kernel/vmlinux.lds.S
> +++ b/arch/hexagon/kernel/vmlinux.lds.S
> @@ -38,6 +38,8 @@ SECTIONS
>         .text : AT(ADDR(.text)) {
>                 _text = .;
>                 TEXT_TEXT
> +               IRQENTRY_TEXT
> +               SOFTIRQENTRY_TEXT
>                 SCHED_TEXT
>                 CPUIDLE_TEXT
>                 LOCK_TEXT
> --
> 2.32.0.rc0
>


-- 
Thanks,
~Nick Desaulniers